I had a conversation with Tissimo asking about timing and its purpose. After that I started to research and this is what I found. Thought I could share with you guys
The stock 1jz ECU has a very conservative timing map.
Follow me in this senerio:
Stock Twins, 1st gear
@ 1500rpm you feel the twins start to spool timing is aggressive to get them going
@2500rpm twin are @ full spool & ECU pull a bit of timing to smoot out power curve
3000-4000 rpm still full spool but ECU starts to add timing to hold up the power curve to about 5500
@ 5800-6200 Still full spool but twins can't supply enough air to keep up with the powerband
@6500 ECU has reached its peak in timing and can't add more timing otherwise it will start to get knock
6500-7200(redline) powerband steadily drops off ( in many cases it starts to drop off by 5800rpm)
NOW, SAME CAR BUT NOW IT'S SINGLE TURBO (GT4082,.68 A/R) STOCK ECU & SAFC.
@1500 car is bit peppy due to timing being somewhat aggressive to spool the twins, but there are non
@2800 I hear the single spooling but no power response is felt. The reason, the ECU's timing map is set to pull timing at this range because that's were the twins would be at full spool.
@3000-4000rpm, GT40 is screaming but still in lag mode, timing is absent therefore not enough psi from the single to create any powerband.
@4000-4200rpm, this is were the ECU adds timing to keep the powerband for the twins, therefore giving the GT40 the timing that it needs to spool and create some good power.
4200-7200rpm, seems like the timing is about leveled and relys on the knock sensor to pull timing if need be.
In Conclusion: The remedy to lag on a 1jz is mainly adjusting the timing to be in accordance with the turbo's characteristics. Your backhousing has something to do with it aswell. You can use an upgraded ECU (i.e. Mines, Blits, SARD,etc...) which normally has a more aggressive timing map that will assist in spooling a single turbo or a piggy-back such as an emanage blue or ultimate that will allow you to change the timing curve.
Here is my dyno sheet. If someone has a stock twin dyno sheet to compare, would help clarify my findings. Add or comment on this as you wish we can all benefit from this info and whoever else can add to this.
The stock 1jz ECU has a very conservative timing map.
Follow me in this senerio:
Stock Twins, 1st gear
@ 1500rpm you feel the twins start to spool timing is aggressive to get them going
@2500rpm twin are @ full spool & ECU pull a bit of timing to smoot out power curve
3000-4000 rpm still full spool but ECU starts to add timing to hold up the power curve to about 5500
@ 5800-6200 Still full spool but twins can't supply enough air to keep up with the powerband
@6500 ECU has reached its peak in timing and can't add more timing otherwise it will start to get knock
6500-7200(redline) powerband steadily drops off ( in many cases it starts to drop off by 5800rpm)
NOW, SAME CAR BUT NOW IT'S SINGLE TURBO (GT4082,.68 A/R) STOCK ECU & SAFC.
@1500 car is bit peppy due to timing being somewhat aggressive to spool the twins, but there are non
@2800 I hear the single spooling but no power response is felt. The reason, the ECU's timing map is set to pull timing at this range because that's were the twins would be at full spool.
@3000-4000rpm, GT40 is screaming but still in lag mode, timing is absent therefore not enough psi from the single to create any powerband.
@4000-4200rpm, this is were the ECU adds timing to keep the powerband for the twins, therefore giving the GT40 the timing that it needs to spool and create some good power.
4200-7200rpm, seems like the timing is about leveled and relys on the knock sensor to pull timing if need be.
In Conclusion: The remedy to lag on a 1jz is mainly adjusting the timing to be in accordance with the turbo's characteristics. Your backhousing has something to do with it aswell. You can use an upgraded ECU (i.e. Mines, Blits, SARD,etc...) which normally has a more aggressive timing map that will assist in spooling a single turbo or a piggy-back such as an emanage blue or ultimate that will allow you to change the timing curve.
Here is my dyno sheet. If someone has a stock twin dyno sheet to compare, would help clarify my findings. Add or comment on this as you wish we can all benefit from this info and whoever else can add to this.
